Development of a core outcome set for the evaluation of shared decision-making interventions in healthcare: a study protocol.

introductionShared decision-making (SDM) is a process whereby patients are supported to reach decisions about their healthcare in collaboration with healthcare professionals. Despite decades of SDM research, the impact of using SDM interventions (eg, patient decision aids, decision coaching, question prompt lists, training and feedback or service changes) on clinical and health service outcomes remains uncertain. This is partly because synthesis of the existing literature is hindered by substantial heterogeneity in the evaluation of interventions to facilitate SDM. A core outcome set (COS) is an agreed standardised set of outcomes that should be measured and reported in all effectiveness studies. The aim of this study is to develop a generic COS for evaluating the impact of SDM interventions (COS-SDMi). METHODS AND ANALYSIS: This study will follow Core Outcome Measures in Effectiveness Trials (COMET) handbook and Core Outcome Set-STAndards for Development (COS-STAD) and reporting (COS-STAR). Relevant key interest holder groups include health professionals, patients, academic experts in SDM, representatives from policy/guideline development, journal editors and research funders. The scope of the COS was agreed through consultation with experts from key interest holder groups. The study will consist of three steps. In Step 1, we will produce a 'long' (comprehensive) list of candidate outcome domains using multiple data sources. Relevant outcomes will be extracted from a COS developed in the context of rheumatology, a synthesis of existing reviews of SDM interventions and qualitative interviews with a minimum of 20 representatives of key interest holder groups internationally. In Step 2, we will agree on a shorter list of outcome domains using a Delphi survey. A sequential two-round international online Delphi survey with two panels (professionals, public/patients) will be used to agree on the outcomes, seeking responses from a minimum of 150 international participants representing key interest groups. In Step 3, we will reach consensus on the final COS using consensus meetings. Consensus meetings with key interest holder group participants internationally will be held, applying modified nominal group techniques. The total project period will be from June 2025 until September 2026. ETHICS AND DISSEMINATION: Research ethics approval has been granted in the UK for undertaking qualitative interviews (University of Exeter Faculty Ethics Committee, ref: 8207624) and the Delphi survey and consensus meeting activities (University of Bristol Faculty Ethics Committee, ref: 7741). Written informed consent will be obtained digitally from all participants in the qualitative interviews, the Delphi surveys and the consensus meetings. The final COS will be disseminated through presentations at international conferences, briefing notes to key organisations and publication in a peer-reviewed journal. Further dissemination is planned through our patient/public advisory group, professional networks and executive group channels, as well as publications to patient groups, funders, journal editors, international regulatory bodies and health technology assessment boards. STUDY REGISTRATION: COMET Database (www.comet-initiative.org/Studies/Details/3586).